SPRING THEATER: PERFORMANCE; Class Clown Makes Good, Quietly

TO audiences at the current revival of August Wilson's ''Ma Rainey's Black Bottom,'' Anthony Mackie is the young man who, in a show lasting some three hours, basically has just one line. His character, the singer Ma Rainey's stuttering nephew, is supposed to say the line as an introduction to one of the songs being recorded, and he repeats it over and over, trying to do it without stammering, in a performance that Howard Kissel in The Daily News called ''funny and touching.''

But to Mr. Mackie, the 10 minutes or so when he is the center of attention at the Royale Theater mean more to him than just his debut on Broadway -- a debut that comes very soon after his Obie-winning performance in Carl Hancock Rux's play ''Talk'' and his screen debut as Eminem's chief rival rapper in ''8 Mile.'' It is an opportunity for Mr. Mackie, 24, to work with people he credits with helping to inspire him to make a life as an actor.

Growing up in New Orleans as the son of a roofer, Mr. Mackie was introduced to the theater in fourth grade as a form of medication. ''I was a bad student, the class clown,'' he said recently. ''All my teachers were like, 'You should put him on Ritalin.' That's the drug they prescribe for kids who are diagnosed with Attention Deficit Disorder.'' Instead, the diagnosis was boredom and the prescription was Sandra Anderson Richards's drama class. ''She became like my second mom,'' he said.

By age 16, he was playing Edmund in a local production of ''King Lear,'' and though he was one of the bad guys, when he was run through by a sword about five girls stood up spontaneously in the audience and gasped, ''Anthony, no!''

''As I lay there dying,'' Mr. Mackie said, ''I realized I wanted to do this for a living.''

About the same time, he first saw Charles S. Dutton in the ''Hallmark Hall of Fame'' television version of ''The Piano Lesson,'' also by Mr. Wilson. Now he is ''thrilled'' to be both Mr. Dutton's colleague and his understudy.

In search of audition material while he was enrolled in a program for high school seniors at the North Carolina School of the Arts, Mr. Mackie was told that he should look up the plays of August Wilson. (He had not realized that Mr. Wilson was the author of ''The Piano Lesson.'') When he read ''Fences,'' about a warring father and son, ''I cried like a baby,'' he said. ''I called up my dad and I told him that I loved him. Then I read all of his plays in two days.''

A year after that, when he moved to New York to attend Juilliard, the first Broadway show he saw, ''A Funny Thing Happened on the Way to the Forum,'' starred Whoopi Goldberg, who now plays his aunt, Ma Rainey.

If ''Ma Rainey's Black Bottom'' is rooted in the blues, Mr. Mackie's music of choice is clearly rap. He produced rap shows when he was a teenager, played the murdered rapper Tupac Shakur in ''Up Against the Wind'' at New York Theater Workshop in 2001 while still a student at Juilliard, and wrote his own raps for ''8 Mile.'' His admiration for most practitioners of this art form, though, is considerably more restrained than his respect for theater performers. ''About 93 percent of the people in rap are talent free,'' he said.

The rapper he respects above all others is William Shakespeare: ''He is the original rapper. If anybody tells you different, they lie. What is Tupac's 'Me and My Girlfriend' but 'Romeo and Juliet'?'' To demonstrate, Anthony Mackie recited the rap, in iambic pentameter. JONATHAN MANDELL